The review was ordered by Republican President Donald Trump earlier this year.

It is widely seen as a preamble to loosening fuel standards, handing a victory to the auto industry.

Rules set by the EPA may, however, take a back seat to consumers demanding vehicles that guzzle less gas and automakers having to meet strict standards if they want to sell cars overseas, according to auto industry analysts.

"We want to increase public participation, listen to those impacted directly by our regulations and use the best available information and data to inform our regulatory actions," EPA Administrator Scott Pruitt said in a statement.

The Obama administration's rules, negotiated with automakers in 2012, were aimed at doubling average fleetwide fuel efficiency to 54.5 miles per gallon by 2025, although the real-world mileage figures would be lower.

The review covers vehicle model years 2022 to 2025. The EPA is also seeking comments on whether fuel standards for the 2021 model year "are appropriate."

The public comment period will be open for 45 days.

Environmental and consumer groups criticized the ongoing process to review the Obama-era standards.

"If automakers are allowed to slack off on making cars run more efficiently, Americans will be forced to spend thousands of dollars more on gas, instead of on their families," Jack Gillis, public affairs director of the Consumer Federation of America, said in an emailed statement.